1. Field of the Invention
The present invention relates to a cleaning device used in an electrophotographic copier, facsimile machine, printer, or the like, particularly to a cleaning device which reduces noise occurring between a cleaning blade and a photoconductor and improves the cleaning performance, and a process cartridge and an image forming apparatus each including the cleaning device.
2. Description of the Related Art
Most of measures for preventing noise occurring in an image forming apparatus such as a copier and a printer have been passive measures using a sound absorbing material or a sound insulating material. Meanwhile, the concept of active noise control of intentionally emitting sound of the reverse phase to the phase of noise to interfere with and cancel the noise has existed for a long time. However, the practical application of the active noise control had not been attained due to the need for an advanced technology.
It is only in recent years that the active noise control has been practically applied along with developments such as the advancement in the signal processing technology. Well-known techniques of the active noise control have been applied to a refrigerator, a vehicle, and so forth. The techniques are for emitting sound of the reserve phase to the phase of noise through a speaker or the like to interfere with and cancel the noise.
In an example according to a background technique, the active noise control method is applied to a vehicle and so forth. Further, in an example according to another background technique, the active noise control method is applied to a copier. According to the background techniques, sound of the reserve phase to the phase of noise is emitted through a speaker or the like to interfere with and cancel the noise. As in such background techniques, sound deadening devices according to the passive noise control method and sound deadening devices according to the active noise control method have been effectively used to prevent noise generated by office automation equipment and so forth from leaking outside the equipment. Further, to reduce noise caused by a charging process, according to another background technique, a dynamic damper is provided to a photoconductor drum, which is a member applied with vibration, to reduce the vibration of the drum and thereby reduce resultant noise.
Meanwhile, in a photoconductor unit and so forth of an image forming apparatus, stick-slip occurs due to the friction generated between a cleaning blade and a photoconductor. Further, vibration resulting from the stick-slip acts as a vibration source to generate high-pitched noise from the photoconductor, or is propagated from the cleaning blade to a unit housing to generate noise. A cleaning device is indispensable to remove residual toner. Thus, the reduction of the noise is desired. The vibration source causing the noise is the stick-slip. The vibration mode of the stick-slip is the self-excited vibration. The occurrence or non-occurrence of the self-excited vibration mode is highly unstable, i.e., the self-excited vibration mode is an unstable mode in fixed value analysis. The unstable mode varies depending on the contact sliding state between the cleaning blade and the photoconductor. The unstable mode may occur or may not occur depending on the combination of a variety of conditions, such as the change in the physical property value of the cleaning blade caused by the change in the internal temperature or humidity of the image forming apparatus, the deterioration of the cleaning blade over time, and the adhesion of toner on the photoconductor. Even in the same configuration, therefore, such a phenomenon occurs in which the vibration noise attributed to the stick-slip suddenly occurs one day or the vibration noise occurs or does not occur depending on the environment of the installation location of the cleaning blade.